Modified 4-member gaussian projection objective



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A ril 2, 1968 M. HUDSON Filed Aug. 28, 1964 TAu AND SAGIT ASTIGMATISM,

FIG. 5

FIG. 2

N m m 5 ,1... z m m u 0m R v m. mwwlouo uJOZ D G-m. :4: m" -H 5 LENA a. nu'oson INVENTOR United States Patent ()flice Patented Apr. 2, 1968 ABSTRACT OF THE DISCLOSURE A modified Gaussian photographic objective having a relatively wide total field angle of at least 64 degrees within which the chromatic and mono-chromatic image aberrations are very well corrected.

This invention relates to improved photographic objectives of the type having at least five elements. I

The lenses disclosed and claimed herein are applicable for a wide range of uses. For example, a preferred embodiment of the invention is particularly suited for a wide angle lens on a 35 mm. camera. Advantageously, the astigmatism, curvature of field and lateral color are fully corrected for an angle of 32 to thereby provide a full field of 64. In addition to having well corrected rim rays, the spherical aberration, coma and chromatic aberration on the axis are well corrected.

Additionally, the novel lenses according to a second embodiment of the invention are particularly applicable for aerial photography since it offers exceptionally good correction. For aerial photography the lenses have been constructed having 3' 6" and 12" focal lengths.

Furthermore a third embodiment of the invention having an F number of f/6.0 has been found to otter additional advantages as a copying lens. Even though the lenses disclosed herein operate in an advantageous manner at infinite conjugates, they have also been found to operate at finite conjugates with magnifications of around 14.5 x to infinity. This lens with a relative aperture of approximately f/ 6.0 has excellent image forming qualityv ture of the lens business makes it highly desirable to produce lenses of superior optical performance while maintaining or reducing the manufacturing costs thereof. The

present lenses have improved optical characteristics as set forth in the preceding paragraphs and as shown hereinafter, and also comprise a structure which facilitates manufacturing procedures to thereby reduce the overall cost of the finished lens assemblies. For example, only two of the lenses are cemented together while the others are airspaced. Additionally the curves withthe exception of the second component and one surface of the third component are relatively fiat so that the manufacturing of the individual components is relatively inexpensive for a system of the present type.

'Briefly, the lenses according to the present invention include five elements except for the third embodiment which includes six elements. The first two elements comprise a positive and a negative meniscus lens respectively. The third and fourth elements are cemented together and form a complex negative meniscus lens wherein the third element is a double concave lens of negative power while the fourth defines a double convex surface of positive power. The fifth element defines a positive meniscus lens with the two radii facing a diaphragm D. The diaphragm D is located between the second and third elements of the system at an axial distance 8,; from front lens element II and distance S from rear lens member III. The elements according to the present invention also conform to .the data set forth in Table A for any of the three forms shown.

TABLE A TABLE 13 The dimensions for the radii of curvature of the various surfaces as multiples of the equivalent focal length F of the entire lens are set forth in the following Table C.

The minus sign used in the table with the R values denotes that such a surface is concave toward the front of the objective so that its center of curvature lies on the front side of the surface.

TABLE C The invention will now be described in'more detail in connection with the accompanying drawings; in which,

FIG. 1 is an optical diagram through an objective lens according to a first embodiment of the invention;

FIG. 2 is a graphical illustration showing the spherical aberrations of the lens shown in FIG. 1;

FIG. 3 is a graphical illustration showing the tangential and sagittal astigmatism of the lens shown in FIG. 1;

FIG. 4 is an optical diagram through an objective lens according to a second embodiment of the invention; and

FIG. 5 is an optical diagram through an objective lens according to a third embodiment of the invention.

First embodiment The objective lens according to a first, i.e., the preferred embodiment of the invention is particularly adapted for use as a wide angle lens on a 35 mm. camera and is illustrated in FIGURE 1. In that form the objective has a relative aperture of approximately f/2.8 and a total field angle of approximately 64, The distinguishing features of the lens element according to the presently preferred embodiment of the invention are achieved by a novel dis tribution of focal lengths or radii and the thickness and spacings of the elements set forth herein. For example, the preferred values of the radii, thicknesses and spacings in terms of F which is the equivalent focal length are shown in Table D.

wherein the minus sign designates those surfaces which are concave toward entrant light.

The following Table E shows the preferred range of values for the radii, thicknesses and spacings of lens elements according to the first embodiment of the invention.

TABLE E TABLE D F R 0.3314 R 0.8345 R 0.2971 R, 0.2074 R5 0.2206 R, 0.7228 R 0.7228 -R, 0.3086 -R9 3.3143 -R 0.5945

s, 0.0014 s 0.1203 s 0.1203 s, 0.0014

The numerical data for the lens system according to a preferred form of the first embodiment of the invention is set forth in the following Table F.

wherein R to R are the radii of the lens surfaces and the minus sign means that such a surface is concave toward the front of the objective, t to t are the axial thicknesses, S, to S are the axial spacings between the successive lenses except S and S which are the axial distances between the diaphragm D and elements II and III respectively, and wherein n to n are the indices of refraction and 1 to 11 are the Abbe numbers of the elements I-V respectively.

Second embodiment The lenses according to the second embodiment of the invention are shown in FIG. 4, Those lenses have been found to be particularly applicable for aerial photography and have been constructed with 3", 6" and 12" focal lengths. The lenses according to this embodiment are particularly well corrected for spherical, astigmatism, distortion, coma and chromatic aberrations. They also have a field angle of approximately 56 and a back focus of about 72 mm. as compared to an equivalent focal length of mm. The values of the radii, thicknesses and spacings of the lens elements in terms of F the equivalent focal length for the second embodiment are shown in Table G.

TABLE G F R 0.3315 R 0.8333 R i 0.2971 R 0.2073 -R5 R -t 0.7231 R 0.7231 -R 0.3197 2.9383 R 0.5626

TABLE G (Cont) F wherein the minus sign designates those surfaces which are concave toward entrant light or the front of the objective.

The following Table H shows the preferred range of values in mm. for the radii, thicknesses and spacings of the lens elementsaccording to the second embodiment of the invention.

The numerical data for the lens system according to a preferred form of the second embodiment of the invention is set forth in the following Table I TABLE I [E.F.L.=100 B.F.=72.06 fields 56 //2.8]

Thickness Index of Abbe Element Radius or spacings Refraction Number R1 =33. I 1. =7.41 m=1.6200 14-603 S1=0.13 R; =29.71 II v e, =s.ao m=1. 7506 i,=27.s

R4 =2o.7a

s,=1a.12 S|=10.90 -11; =22.1s III n =2.07 "i=1. 7200 v3=29.3 R. =72.31

R1 =72.a1 rv' t. =9.0e "i=1. 7200 1q=47.5

S4=0.13 Ra =29as3 v' n =e.o4 m=1. 7506 v5=27.8

, Riu=56.26 v

wherein R to R are the radii of the lens surfaces and the minus sign means that such a surface is concave toward the front of the objective, t to t are the axial thicknesses of lens elements I' to V, S to 8., are the axial spacings between the successive elements except S and S; which are the axial thicknesses between thediaphragm D and elements II and III respectively and wherein n; to u are the indices of refraction and il to 1' are the Abbe numbers of the elements I-V respectively.

6 Third embodiment The lens-system according to the third embodiment of the invention has been found to operate at finite conjugates with magnification of around 14.5 to infinity.

The system has been found to be particularly suitable for v use in copying, having a F number of f/ 6.0 and holding excellent image forming qualities over a field of approximately 50. The lens elements according to the third embodiment are characterized by the following values of focal lengths and surface radii and thicknesses and spacings of the elements shown in Table K.

TABLE K The following Table L shows the range of values for the radii, thicknesses and spacings of a lens system according to the third embodiment of the invention.

TABLE L The numerical data for the preferred form of the lens system'according to the third embodiment of the invention are set forth in the following Table M.

TABLE M [E.F.L.=l00.0 B.F.=7l.16 field 50 //6.01

Thickness Index of Abbe Element Radius or Spacing Refraction Number R =32.96 I tr =7.4l m=l.6200 v =60.3

Sr=0.14 R1 =29. II" l3 =5.3O flg=l.7506 93 27.8

Sr=13.12 Sr=10.95 -R =22.23 III t; =2.08 n =l.7200 v|=29.3

Rs =72.55 R1 =72.55 IV" 4 =9.05 m=1.7200 v4=47.5

S4=0.14 -R =293A8 V" 5 =6.03 fls=1.7506 V5=27.8

S;=73.95 R1r=Pl8n0 VI I. =6.27 m=1.5240 n= 59.5

Ru=Plano wherein R to R are the radii of the lens surfaces and the minus sign means that such a surface is concave toward the front of the objective, t to t are the axial thickness of the lens elements I" to VI, S to S are the axial spacings between the successive lens elements I" to VI except S and 8;, represent the axial spaces between the included diaphram D and the element II" and III" respectively, and wherein In to u are the indices of refraction and v to 11 are the Abbe numbers of the elements I-VI respectively.

While the invention has been described in connection with several examples it should be understood that it may be modified and embodied in other forms without departing from the scope of the appended claim.

What is claimed is:

1. An objective lens including six elements, a first .of said elements comprising a positive lens I" and a second of said elements comprising a negative lens II", a third 'and a fourth of said elements cemented together to form a complex negative meniscus lens III", IV", a diaphragm D separating said second and said third elements, a fifth member V' comprising a positive lens, and a sixth mem-.

ber comprising a glass plate VI, s'aid elements conforming substantially to the following conditions:

[E.F.L,=100.0 B.F.=71.16 field 50 [/60] Thickness Index Abbe Element Radius or Spacing Refraction Number m) R =32.96 v I". i1 =7.41 'm=1.6200 v1=60.3

S1=0.14 R: =29J2 II- t =6.30 n =1.7506 v;=27.8

8 :13.12 Sz=10.95 R5 =22.23 III t1 =2.08 m=l.7200 'v;=29.3

' R. =72.55 r B1 =72.55 10 IV" n =9.05 m=1.7200 w=47.5

S4=0.l4 Ro =293.48 v" l =6.03 125=L7506 v5=27.8 R1o=56.70 v Sr=73.95

' 11; 3110 R Pl VI h =6.27 m=1.5240 v =59.5

Ru=Plano wherein R to R are the radii of the lens surfaces and the minus sign means that such a surface is concave toward the front of the objective, 1 to 1 are the axial thickness of lens elements I to IV, S to S are the axial spacings between the successive lens elements I" to VI except S and S which are the axial distances from the included diaphragm D to elements II" and III" respectively and wherein In to n are the indices of refraction and v to v are the Abbe numbers of the elements IVI respectively.

References Cited UNITED STATES PATENTS 2,744,447 5/ 1956 Berger et a1. 350-209 2,799,207 7/ 1957 Lange 350209 FOREIGN PATENTS 779,614 7/1957 Great Britain.

DAVID'H. RUBIN, Primary Examiner. JEWELL H. PEDERSEN, Examiner.

R, J. STERN, Assistant Examiner. 

